An increasing demand exists for pre-fabricated structural panel materials, such as plywood, wafer board, oriented strand board, plaster board, composites of veneer and of wood-based layers, and so forth. These structural materials are heavily used, for instance, in the construction and manufacturing industries. Suppliers and users of these products often need to know their flexural properties, e.g., elastic and strength properties, to assist them in making a proper material selection. Specimen or control panels cut from large panels or pulled from a given production lot are tested to determine the flexural properties of the panel material. It is imperative that the testing arrangement used for these tests yields accurate, reliable and repeatable results to increase confidence that the control panel results are representative of the entire production lot.
Devices for performing flexural tests on sheet or strip materials are known which are configured to apply a controlled load to a testing panel while concurrently recording the deflection of the test panel as the load is applied. For instance, for a known test panel geometry, load and deflection data can be measured on such devices during a test cycle. The panels are flexed and deflection measured to determine panel modulus and stiffness, and flexure is continued until rupture to determine the panel strength.
U.S. Pat. No. 3,286,516 describes a machine for performing flexural test on panels comprising a force producing means connected to a cable and pulley system which converts the force to opposite torques acting about parallel axes, in which loading frames are mounted on both torque axes for applying torques to a flexure specimen. A torque measurement apparatus is mounted on one of the torque axes, and the torque axes are supported on carriages and tracks for free rotation and lateral movement. Among other drawbacks, the cables can stretch, and the device can get out of calibration as the cables stretch, requiring their replacement. Also, depending on the panel strength needed, different sizes of cables may need to be installed on the device to test different thicknesses of test panels.
U.S. Patent Application Publication No. 2003/0192385 A1 describes a panel bending and testing device in which the drive system is powered by pneumatics and hydraulics.
A panel testing device which provides accurate and repeatable results with reduced parts maintenance requirements would be desired by those skilled in the art.